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W. M. DUNCAN.

FURNACE.

APPLICATION FILED Nov. 20. x915.

WH ;w W mm; W a ma 1% W."M. DUNCAN.

FURNACE.

APPLICATION FILED NOV. 20. 1915.

Patented Sept. 23, 1919.

3 SHEETS-SHEET 2.

W. M. DUNCAN.

FURNACE.

APPLICATION HLED Nov. 20. 1915.

Patented Sept. 23, 1919.

3 SHEETS-SHEET 3.

UNITED STATES PATENT OFFICE.

WILLIAM M. DUNCAN, OF AL'I'ON, ILL'INOIS.

FURNACE.

Speciflcation of Letters Patent.

Patented sept. 28, 1919.

Application filed November 20, 1915. Serial No. 62,508.

` which the following is a full, clear, and exw act description, reference being` had to the accompanying drawings, forming a part of the specification.

My invention relates to a furnaceequipped with a mechanical stoker and other elements adapted to be associated therewith to provide for the combustion of anthracite coal on a traveling chain grate.

In the prior structures the coal receptacle is usually located a-t the front of the furnace and at a point outside of the fire box, and the chain grate traveling under the coal receptacle, carries the fuel toward the rear of the furnace. usually include an ignition arch lfor transmitting the heat by radiation to the green coal, and the hot gases flow' rearwardly, away from the green coal. My improved anthracite burner differs essentially from the prior structures referred to, and owing Ato this difference the new structure is Well adapted for use in burning anthracite coal.

In the preferred form of the invention, the coal receptacle is located within the fire box at a point above the rear portion of the traveling' chain gra-te. The grate passes under the coal receptacle at the rear of the furnace and carries the fuel toward the front of the furnace, the parts being so arranged that the hot gases passing from the fuel are directed backwardly wlth respect to the movement of the grate. The coal receptacle is thus located-at a point Where it will be subjected directly to the heat of the fire box, the hot gases being directed backwardly toward the coal receptacle and the latter being preferably open at the top so that the coal contained therein Will be sub- 'ected directly to the heat of said gases.

y constructing and arranging the arts in this manner the coal may be place in an incandescent statebefore it Lreaches the traveling chain grate, and it W111, therefore, ignite before or immediately after leaving the receptacle. Since the hot gases are directed backwardly, toward the coal receptacle the coal will burn very readily after leaving` the coal receptacle.

With the foregoing and other objects in These earlier structures view the invention'comprises the novel construct1on, combination and arrangement of parts hereinafter more specifically described and illustrated in the accompanying drawmgs wherein is shown the preferred embodiment of the invention; however, it is to be under'stood that the invention comprehends changes, variations and modifications which come within the scope of the claims hereunto appended.

Figure I is a longitudinal section of a fur- J:race embodying the features of my inventhe endless fuel carrlers and the draft box associated therewith, some of the fuel carriers being' omitted.

Fig. III is a Vertical section taken approxlmately on the line III-III, F ig. I.

Fig. IV is a detail view of the means for Operating the gate, or barrier, at the front of the furnace.

1 designates the side walls of a furnace, and 2 designates tracks located between said side walls. Side frames 3 and 4; are provided with Wheels which rest upon the tracks 2. A drive shaft 5 mounted in the side frames at the front of the grate is provided with a series of sprocket Wheels 6 which lie between the side frames 3 and 4:. An idle shaft 7 at the rear of the grate, is provided with idle Wheels 8. The Wheels 6 and 8 constitute supporting elements for a series of traveling fuel carriers, and each of these fuel carriers comprises an endless sprocket chain 9 :fitted to one of the s rocket Wheels 6 at the 'front of the grate an also fitted to an idle wheel 8 a the rear of the grate. Each fuel sup orting member is a rectangular plate 10l aving perforations for the admission of air to the fuel and provided with legs, the ends of said legs bei 0' secured to the pivot pins forming part o the endless Chain structure. i

To p'revent undue leakage of air fuel, the fuel supporting` members 10 lap each other as shown in Figs. I 'and III.

II will now describe the means for controlling the flow of air to different parts of the fuel bed. Manifolds 12, 13 and 14, arranged transversely of the chain grate structure, are secured at their ends to the side frames 3 and 11. Air conducting pipes 15, passing through a furnace wall 1, are fitted to the manifolds and provided with valves 16 for regulating the flow of air through the mani- Fig. II is a top or. plan view illustratingfolds. Each valve 16 is adapted to control the draft inonly one of the manifolds, and these valves may be adjusted independently 'of 'each other to vary the draft at different parts -ofthe fuel bed. Any suitable blower, or blast device, may be used for forcing air through the air conducting pipes 15.

The draft boxes for conducting air from the manifolds to ,the fuel bed, are arranged longitudinally of the grate, and each manifold is in communication with a series of the draft boxes. The manifold 12, near the front of the grate, communicates with draft boxes 17 and 17', the boxes 17' being located at the sides of the grate, as shown in Fgs. II and III, and the draft boxes 17 being located between said draft boxes 17'. Eachl of the draft boxes 17 and 17' is closed at its sides and ends, and open at the top to permit the air to circulate through the perforations in the fuel supporting members 10. The different draft boxes are separated from each other to provide passageways for the endless sprocket chains 9 which travel between said draft boxes.

Intermediate draft boxes 18 and 18', similar to the draft boxes 17 and 17', are'lprovided with end walls 19 and bottom and side walls. connectingv said end walls. All of these intermediate draft boxes 18 and 18' are in communication With the manifold 13, and they are separated from each other to permit the sprocket chains topass between them. Rear draft boxes 20 and 20' are provided with end walls 21 connected by side and bottom walls, said rear draft boxes being in communication with the rear manifold 14.

The front, intermediate and rear draft boxes are connected together to formLV several longitudinal rows of draft boxes, but the draft boxes 17-17', near the front of the grate, are not in communication with the intermediate or rear draft boxes, and the intermediate draft boxes 18-18' are not in communication with any of the other draft boxes. The air passing through the manifold 12 is forced through the fuel supporting members and into the fuel bed at points immediately above .the draft boxes 17-17', the air forced through the manifold 13, passes through the intermediate draft boxes and into the fuel bed above said boxes; and the air forced through the rear manifold 14 passes upwardly from the rear draft boxes 20 and 20' at points between their end walls 21. It will be observed that the draft boxes are arrange'd to form three draft zones,--one near the front of the grate, one at the middle portion of the grate and, one at the rear. The draft in any one of these zones may be regulated by adjusting one of the valves 16, and the draft in any one zone maybe varied without changing the draft in any other zone. Although the draft is preferably created by forcing air through all of the manifolds 12, 13 and 14, it is to be understood that very satisfactory results may be obtained by drawing air downwardly from the .rear draft boxes and through the manifold 14, thereby creating an induced draft at points immediately above the rear' portion of the grate.

22 designates tracks arranged in the upper portions of the draft boxes to receive the lapped marginal portions of the fuel supporting members 10. Guide members 23, extending forwardly from the front ends of the draft boxes 17, are adapte'd to guide the a rock shaft 27 having a series of arms 28,

the upper ends of said arms being secured to the closures 25 near the front of the grate.

v The means for actuating the rock shaft 27 comprises an arm 29 secured to one end of said rock shaft, and an Operating rod 30 connected to said arm. When the grate is in.

service, ash, etc., will drop through the perforations in the fuel supporting members.

and fall onto the bottom walls of the draft boxes. Such material may be removed by opening all of the closures 25 when lthe air under pressure is flowing into the draft boxes. When these closures are open, the air will escape freely through the discharge openings 24, thereby blowing the ash, etc., through said openings and onto the lower course of fuel supporting members. This materialwill be 'conducted rearwardly by the fuel supporting members and discharged therefrom at points near the rear of the grate.

In the preferred form of the invention, a coal receptacle 31 (Fig. I) is located in the fire box at a point immediately above the rear portion of the traveling grate. coal rcceptacle is open at the top to receive thecoal, and open at the bottom to permt the discharge of coal onto the grate. designates water tubes extending across the furnace at points adjacent the coal receptacle 31. A second coal receptacle 31' (Fig. I) is located outside of the fire box in a plane abovethe coal recepta'ole 31, and provided wit-h a discharge opening 31". The means for feeding coal from the coal receptacle 31', comprises a .pusher, or plunger 33, arranged in the lower portion of said coal receptacle at a point opposite the discharge opening 31". 34 designates a guide rod secured to the -pusher 33 and connected to a crank 35 This fss

by means of a pitman 36. The cranl; 35 is driven through the medium of a sprocket wheel 37, and a sprocket chain 38 passing over said sprocket wheel 37 and fitted to a sprocket Wheel 39, the latter being fixed to one end of the drive shaft 5. The power mechanism includes a worm wheel 40 fixed tothe driveshaft 5 (Fig. II) a worm 41 fitted to said worm wheel'40, and a power shaft 42 fixed to said worm. The pusher 33, in the coal receptacle 31' moves in unison With the endless chain grate, and a predetermined quantity of fuel is pushed through the discharge opening 31" at regular intervals, the driving mechanism being so constructed and 'arranged that any change in the rate of travel of the chain grate will result in a corresponding Variation in the speed of the reciprocating pusher 33.

The arrows shown in full lines Figure I indicate the direction of movement of the coal, and the arrows shown by dotted lines indicate the direction of flow of the hot gases. The coal discharged from the local receptacle 31' drops into the receptacle 31,

and it may be permitted to accumulate therein as indicated by dotted lines. It Will 'be noted that the coal passing from the bottom of receptacle 31 is carried forwardly by the traveling chain grate, and .that the hot gases travel backwardly with respect to the moyement of the coal. The coal receptacle 31 and the coal contained therein, is, therefore, subjected directly to the heat of the gases. The coal becomes very hot before it reaches the traveling chain grate and it may be ignited at the lower portion of the coal receptacle 31, or at a point immediately in front 'of said receptacle. After passing from the coal receptacle, the ignited coal is subjected to the heat of the gases flowing backwardly from the front of the furnace so that it Will burn freely in passing from one end of the furnace to the other. The fuel bed is also subjected to the action of the forced draft passmg through the manifolds 12 and 13, and' the coal in the receptacle 31 is subjected to the action of the draft passing through manifold 14 and draft boxes 20-20' which liedirectly below said coal receptacle. The draft passes through the coal receptacle 3-1, and the 'body of the coal contained therein is heated throughout by the hot gases 'passing upwardly from the grate if a forced draft is created at this point, or downwardly from the top of the coal receptacle if an induced draft is created in the manifold 14. I preferably force the air upwardly from the bottom of the coal receptacle so that the body of the coal will be subJected to the heat passing from the ignited, or incandescent coal at the bottom of said receptacle. By constructing and arranging the parts substantially as herein shown and described, the

apparatus will serve as a highly eflicient means for burning anthracite coal on a traveling chain grate.

Kindling material, such as paper, Wood and bitummous coal, or the like, is placed inthe coal receptacle 31, and ignited before the apparatus is placed in Service. A draft time by forcing air through the manifold 14. Thereafter, the mechanism may be placed in motion to feed the burning fuel away from the coal receptacle, and since the direction of the draft is backwardly with respect to the movement of the fuel, the combustion of the fuel near the coal receptacle is at all times aided by the more completely ignited fuel; The draft in the different manifolds may be regulated to suit the abnormal conditions in starting the fire. The ash is discharged from the grate at the front of the furnace, and-the thickness of the bed of ash at this point may be varied by adjusting a Vertical movable gate or barrier 50. 51 designates sprocket chains. secured to the gate or carrier 50, and also secured to sprocket Wheels 52, the latter bein fixed to a shaft 53.` An Operating han le 54 (F igure IV) secured to shaft 53, may be adjusted to raise and lower the gate or arrier 50, and after such adjustment the parts may bc locked by a pawl 55 fitted to a ratchet wheel 56.

The combination of draft boxes and fuel carriers, arranged as herein disclosed, is

claimed in an application for patent filed by,

me November 20, 1915, Serial No. 62,507, furnaces, renewed May 8, 1919, Serial No. 295,699.

I claimz- 1. In a furnace, a traveling. grate Within the furnace fire-box, a coal receptacle located in said fire-box immediately above said grate, said coal receptacle having an open bottom permitting coal therein to be supported by the grate While confined within a given area above the grate, a'nd means for delivering hot gases to the coal in said receptacle to heat it before it passes to the grate.

2. In a furnace, a traveling grate Within the furnace fire-box, a coal receptacle located in said fire-box immediately above said grate, said coal receptacle having an open bottom permitting coal therein to be supported by the grate while confined within a given area above the grate, and means for delivering hot gases into contact with the exterior of said receptacle and the coal within said receptacle, thereby providing for thorou h heating of the coal prior to its delivery fi'om the receptacle to the grate.

3. In a furnace, a traveling grate within the furnace fire-box a coal receptacle located in said fire-box lmmedlately above said grate, said coal receptacle having an open Amay be created 1n the coal hopper at` this A bottom permitting coal therein to be supported by the grate While confined within a given area above the grate, and means for conducting hot gases to said receptacle in a direction contrary to the direction of movement of said traveling grate.

4. In a furnace, a traveling grate confined Within the fire-box of the furnace, a coal receptacle confined Within the furnace firebox immediately above said grate, said coal receptacle having an open top to receive a supply of coal and an open bottom through which coal is delivered directly onto said grate, said receptacle serving to hold a supply of coal in contact with the grate for delivery thereto, and means for delivering hot gases to the coal in said receptacle, Whereby such coal is thoroughly heated before it passes from the receptacle to the grate.

WILLIAM M. DUNCAN. 

